My last post described a risk-based approach to First Amendment protection of scientific claims, and showed why this shift would constrain some of the legal rules that currently apply to commercial speech. Although a risk-based approach would give the government less latitude to regulate scientific claims made by commercial speakers, it should give the government more latitude to regulate scientific claims made in public discourse. In circumstances where junk science is not only very likely to be false, but also likely to be influential and harmful, fines or liability rules should be able to survive First Amendment scrutiny.

The most tentative section of my article, Snake Oil, makes the case that some forms of “Anti-Knowledge” could be controlled through common law doctrines like negligence without doing mischief to core free speech values.

Let me start by defining some terms. Anti-Knowledge is a subset of factual statements. Free speech law already has to make a distinction between factual and non-factual speech. Factual claims are falsifiable and can, at least theoretically, be compared to objective reality. Non-factual speech (like opinions, moral or political philosophies, and artistic expression) do not assert claims about the objective world and therefore are not falsifiable. Sometimes the division between fact and opinion is hard to make, but courts and lawmakers can and frequently must do this (for example, in defamation law, which applies only to false statements of fact and not to opinions, no matter how hurtful they may be.)

It’s helpful to further subdivide the vast and diverse universe of factual claims into three categories: Accepted Knowledge, Anti-Knowledge, and Contested Knowledge.

Accepted knowledge is comprised of factual claims that that pass an appropriate epistemological standard for “truth.” We shouldn’t pretend that accepted knowledge is the same as truth (for reasons that Thomas Kuhn elaborated), but based on the best instruments and standards for evidence at a given time, a subset of factual claims can be specially recognized as reliable and verifiable.

Anti-Knowledge gets its definition from the Accepted Knowledge category. It contains any statement that is in direct conflict with statements contained in the “accepted knowledge” category. This leaves a large residual category that I have been calling “Contested Knowledge.”

My last post focused on advertising restrictions on Contested Knowledge. Within Contested Knowledge, First Amendment law has under-protected commercial speakers. I do not think that current law or First Amendment doctrine under-protects commercial speakers with respect to Anti-Knowledge. In fact, when it comes to Anti-Knowledge, the First Amendment has over-protected speakers—particularly speakers who engage in public discourse.

There is a popular misconception that Fox News successfully won a legal “right to lie” in a 1990s case involving reporting about dairy farms. Although this folk legal analysis is not correct, it is undeniable that Anti-Knowledge is strongly protected from government interference when a person speaks to a broad, indiscriminate audience about a matter of public concern. The 2012 Supreme Court opinion in United States v. Alvarez (which begins “Lying was his habit”) said in no uncertain terms that false statements are protected by the First Amendment as a general rule. But it also left open the possibility that lies may be regulated if they cause “legally cognizable” harm.

One would think that physical harm is the quintessential “legally cognizable harm,” yet tort cases against publishers and public speakers tend to lose on First Amendment grounds, even in instances where a speaker should know that his falsehood, if believed, are likely to cause grave physical harm or death. In the most famous case along these lines—Winter v. G.P. Putnam’s Sons—the First Amendment protected the publisher of an encyclopedia of mushrooms that assured readers a particular type of mushroom was safe to eat when in fact it was toxic. And other cases I discuss in the full draft suggest the First Amendment supplies broad immunity that protects charlatans, celebrities, and other authors who make pseudoscientific statements in the press or public gatherings.

The strong First Amendment protection for factual claims in public discourse stems from an admirable commitment to epistemic modesty. As the Court said in Alvarez, “Our constitutional tradition stands against the idea that we need Oceania’s Ministry of Truth.” But protection goes too far if it can’t be outweighed by the public interest in deterring reckless anti-knowledge that causes foreseeable physical harm.

What I’m suggesting here runs against the trend to expand and strengthen First Amendment protections (a trend that I’ve supported in most of my work). So consider this hypothetical to test whether liability for pseudo-science can withstand strong free speech scrutiny: should courts or legislators be able to create civil liability for doctors or documentary-makers who publicly provoke fear about trace amounts of mercury used in vaccinations? If the family of a child who has a severe case of measles can provide credible evidence that a book or documentary persuaded his family, or the family of a child who transmitted the disease to him, to avoid the measles vaccine out of unfounded concern that the shot could increase the risk of autism, should the First Amendment come to the speakers’ defense?

It seems to me that the social benefits from this sort of legal intervention are at least as compelling as the benefits from well-working defamation law. It is true that courts will have to determine on a case-by-case basis whether a factual claim was false (that is, whether it is anti-knowledge), whether the authors had a negligent or reckless disregard for the truth, and whether the speech actually influenced listeners. But courts must make these same sorts of factual determinations in defamation law, too.

Although defamation is often listed as one of the special categories of unprotected speech, the principled explanation for those historically unprotected categories is that they mark distinct areas where the non-speech interests outweigh the interests in free speech. Other regulations that target harmful misinformation should be able to prove that they strike an appropriate balance, too, albeit within strict scrutiny instead of outside of it.